A couple of days ago, I wrote about Sonoff POW R2 WiFi switch with power monitoring function that meant to be connected to your mains via terminal, and I was made aware of another product – Eastron SDM120C – that also does power metering, but support up to 45A (good enough for whole house in many cases), and use RS485 / Modbus communication instead of WiFi.

With this type of a deice you’ll want to make sure it’s certified for safety, and it appears to follow many different safety standards, but I’m not knowledgeable enough to confirm whether those are sufficient for Europe. Note that the device is only for 220-230V, so it won’t work in the US. The company claims to have 110V versions, but I could not find them on Aliexpress.

SDM120(C) is sold for $22 and up on Aliexpress, but you’ll also find SDM120 A – which looks similar – , but with single pulse output and a different display, for $11.70. The Domoticz documentation also relies on a RS485 to USB converter for connecting the smart meter to your automation gateway.